b'Education matters Canadian Arctic Islands and consequentMechanical stratigraphy refers tomultiwavelength deformation of the collision with the Koyukuk oceanic- the mechanical layering present in aPapuan Fold Belt. We document the island arc, which resulted in the uplift ofstratigraphic column, involving theinteraction and interference between the the Brooks Range and the formation ofsuccession of competent and lessthick- skinned Darai Plateau trend, and the adjacent foreland basin. They alsocompetent lithologies. For a given setthe thin-skinned Papuan Fold Belt trend.reproduce the sediment depositionalof boundary conditions and amount ofIn our preferred model, the convergence of trends and main provenance areas on theshortening, the mechanical stratigraphythese structural trends is accommodated North Slope of Alaska as observed fromis expected to influence the partitioningthrough the formation of a pop-up wedge the sedimentological record. of shortening between folds and thrusts,in the hanging wall of two conjugate faults, The spatial variation in dynamictheir respective distribution pattern,which are part of a duplex-like structure topography through time resulted intheir respective wavelengths, andwhich consists of a series of hinterland-tilting of the basin which influencedpossibly the nature and expression ofdipping stacked horses. Our results show sediment routing directions. Sea-leveltheir interaction. An understanding ofthat the competent units, such as the Darai fluctuations were found to significantlythe mechanical stratigraphy of a foldlimestone deform via faulting, whereas the slow the depositional system, trappingand thrust belt is crucial for assessingincompetent Mesozoic sediments tend more sediment in the proximal basin.structural traps, fluid flow, and refiningto fold, and contain multiple detachment Notably, during the main phase ofgeologic interpretations. horizons. Models with a calibrated deposition in the basin (115 to 100 Ma),In the first part of the thesis, we runmechanical stratigraphy are able to eustasy resulted in the accumulationtwo-dimensional, coupled thermal andreproduce structures similar to those found of up to 200400 m thicker sequences.mechanical, numerical experimentsin the New Guinea Fold Belt, reveal the Cross-sections of the modelledutilising the Underworld frameworkstructure of the lesser constrained areas deposition of the Aptian to Cenomonianto explore the influence of mechanicalof the fold and thrust belt, and illuminate clinothem across the foreland basinstratigraphy on the structural evolutionsubsurface geometry in the region.were extracted to more closely analyseof fold and thrust belts. We calibrate our the shelf margin evolution. Theynumerical parameters such that we areMonash University, Victoriarevealed that the models reproduce theable to simulate the formation of naturalHonours theseslarge-scale stratal geometries observedfold and thrust belts. This enables us to from the seismic record, as well as thesystematically investigate the structuralHannah Williamson, Monash University: shelf margin trajectory shift at 105styles brought on by the mechanicalHow does the geophysical response of Ma where stratal stacking patternslayering of competent and incompetentcomplex geology translate undercover? shift from dominantly progradationalunits within a stratigraphy. We find thatAn example from the Wonomo Fault, to more aggradational. They suggestmultiple wavelengths of deformation aresouthern Mount Isa Inlier. ASEG Research that sealevel acted to decrease theactivated in our models. Foundation supported projectprogradation rate by 6 km/Myr duringA landscape-scale wavelength of the early longitudinal filling of thedeformation that forms due to the basin (115 to 105 Ma), and that amechanical contrasts within the dynamic subsidence of at least 50 meoverall stratigraphic package, and a experienced by the basin between 110more local wavelength of deformation and 100 Ma was a contributing factor tothat forms as a result of mechanical the abrupt trajectory shift. heterogonies within single units. This This study demonstrates the importancewavelength of deformation gives way of linking deep Earth processes toto a more complex and heterogenous landscape evolution models to gain aset of structures. Our work has led us to better understanding of the long-termconclude that the position of competent evolution of sedimentary basins. layers within a multilayer, in combination with the ratio of competent to Joe Ibrahim, University of Sydney:incompetent rock will have a significant Mechanical stratigraphy, structural styleinfluence on strain partitioning within and the evolution of fold and thrust belts. thin-skinned fold and thrust belts. The southern extension of the Mount Isa Inlier has been largely neglected Fold and thrust belts form as the crustIn the second part of the thesis wefor exploration because of logistical accommodates shortening due tocalibrate a mechanical stratigraphyand technical difficulties of exploring compressional tectonic forces. Thefor the structural styles found in theundercover despite the likelihood of this structural architecture of fold and thrustPapuan Fold Belt, utilising previousregion hosting large mineral systems. belts varies widely and is influencedknowledge about the strain partitioningGeophysical data provides powerful by a multitude of factors including theof the region, and a set of well-imagedinformation on the petrophysical driving boundary conditions, the amountstructures. We aim to propose aproperties of lithologies undercover which of shortening and the level of basementcoherent assemblage of structures incan be used to make interpretations of involvement (i.e. thin-skinned vs thick-the less constrained parts of the Gobeburied geology. However, the reduction skinned tectonics). Here, we investigateregion, which is characterised by thein resolution of aeromagnetic and gravity how the mechanical properties of rocksconvergence of two varying structuraldata with depth and lack of surface control the structural style of fold andtrends. Our models demonstrate theconstraints increases the level of ambiguity thrust belts. control mechanical stratigraphy has onof interpretations. This study analyses the DECEMBER 2019 PREVIEW 42'